9.9. Strings are Immutable¶
One final thing that makes strings different from some other Python collection types is that
you are not allowed to modify the individual characters in the collection. It is tempting to use the
 operator on the left side of an assignment,
with the intention of changing a character in a string. For example, in the following code, we would like to change the first letter of
Instead of producing the output
Jello, world!, this code produces the
TypeError: 'str' object does not support item assignment.
Strings are immutable, which means you cannot change an existing string. The best you can do is create a new string that is a variation on the original.
The solution here is to concatenate a new first letter onto a slice of
greeting. This operation has no effect on the original string.
Check your understanding